Hey there,
My boyfriend and I bought Ed, my second betta, a couple of weeks ago. He's absolutely gorgeous, and I love him to death.
I forget how big my tank is, since I bought it a year or so ago, but it's about a foot long, just under a foot tall, and about 6 inches deep (using my estimation skills - does anyone know how many gallons that might be?). I don't have a heater, but I would like to buy one soon. I just have no idea what to look for.
One of my concerns is that Ed still hasn't eaten. I have pellets, flakes, and dried bloodworms, as well as frozen blood worms. I've been alternating with pellets and flakes for the most part, and have tried blood worms a couple times. At first he would bite on and then spit it out, but at this point he doesn't even pay attention to it. BUT since I've gotten him he's made two bubble nests, which confuses me because from what I know bettas only make bubble nests when they're happy.
I've done two 50% water changes so far.
Does anyone have suggestions for what I should do????

Two 50% water changes as in, when you first got him? If so, you need to start doing them every day, since you're still cycling.
I'll do calculations in a bit

He's probably still acclimating. It's not too rare when it takes a betta weeks to get acclimated. However, lack of heater is definitely not helping in this case (Go to Walmart, they have pretty cheap ones). For food, people do different things, but personally, I would keep pushing with just one single type of food for a week, straight. After a week, I may alternate, but that I use the alternate for a week straight as well. Only a personal tactic, other people do other things. But TBH, neither of my bettas took more than a few days to acclimate.

Sometimes I don't understand why my bettas make bubblenests either, because sometimes their fins will get shredded, and then all of a sudden, a gorgeous bubble nest. What? Lol, sometimes it's random, but I honestly don't understand them in that sense.

Where did you hear that from?lol I use the same pellets and mine are fine. You can mix it up with free-dried blood worms and brine shrimp, but you don't have to. My fish would eat about anything, so they love the pellets. Also, I fast mine once a week because it's good for their digestive systems. I heard recently that bettas don't have to be happy to build bubblenests, they just do it. It's basically an instinct that they have.

Well when I meant "only use one", it should be his STAPLE food (like pellets), the food that he will eat most often. Pellets are probably the best staple food. You don't want him only eating freezedried bloodworms for his whole life, so he must get used to whatever he will be fed most. But of course, feed him varieties!! Lol, get treats for him, feed a couple times a week, or whatevre you prefer.

As for certain heaters, well frankly, the better heaters are the ones that can keep a good temperature without too many fluctuations (try to stray away from pre-set heaters, unless that's all you can really afford), etc etc. Like any good product, basically, reliable. Ask others for their heaters though, mine kinda sucks. Lol

I got a heater just recently, and Ed is MUCH more active, and seems to be a lot happier. However I'm apprehensive about changing his water now... If the water I'm putting in is just room temp and the water in his tank is 78 degrees F, then will that cause him temperature shock?? I don't want to hurt my little boy.

And he's still not eating... I've been feeding him 2-3 pellets twice per day for about four days now and he's still not eating. He's been eating it and then spitting it out again, and then not touching it. Even after they've been soaking for a minute or so.

And this is what is called "finger-testing." You compare the temp. of his tank, and have the new tank water match that as CLOSE as possible. It's a trial and error at first, hopefully you have a thermometer? And it's very possibly he may go into shock, but for some people, room temperature means different things.